Melamine formaldehyde sulphonate

Concrete Additives. Melamine-formaldehyde resins can be sulphonated and then used in fresh concrete to create a plasticizing effect. The resin makes 1) concrete more flowable, thus improving concrete s workability and 2) allowing the water content to be reduced for faster drying times. The end result is an improved, stronger material that is structurally superior. 

Sulphonated melamine formaldehyde condensates Sulphonated napthalene formaldehyde condensates Modified lignosulphonates. 

Sulphonated melamine formaldehyde based superplasticizers tend to reduce air content when used to produce flowing concrete. 

Yilmaz, V. T., and Glasser, F. P., Influence of Sulphonated Melamine Formaldehyde Superplasticizer on Cement Hydration and Microstmctuie,... 

Curing temperatures below 120°C are obtained by additions of acids, such as para-toluene sulphonic acid, acid butyl phosphate, acid butyl maleate or special proprietory catalysts. The combination of acid catalysis and a highly reactive melamine formaldehyde resin can result in curing temperatures as low as 80°C. In such cases the paint formulator must pay careful attention to pigment and viscosity stabilities to ensure that flocculation of the pigment does not occur. Viscosity is normally controlled by primary alcohols in the solvent blend (at least 20% of total solvent). 

Melamine formaldehyde can be crosslinked at elevated temperatures with both hydroxyl and carboxyl functional groups. (See thermosetting acrylics chapter for reaction mechanisms.) The temperature required is at least 120°C, at which point the hydroxyl group will react, but the carboxyl group needs a slightly higher heat input, approximately 150°C. Systems are unlikely to require an acid catalyst because of the catalytic effects of the polymerisation catalysts and surfactants in the acrylic latices. If required, p-toluene sulphonic acid is the most suitable (typically at levels of 0.2 - 0.4%). Alternatively, the melamine resin could be incorporated in an unneutralised, acidic emulsion, which reduces the cure temperature, but will sacrifice stability. 

Acrysol WS-68 is a small particle size emulsion of an acrylic copolymer containing acid groups which solubilise the polymer when the amine is added. Cymel 303 is monomeric melamine-formaldehyde resin which crosslinks the acid groups in the acrylic copolymer. The p-toluene sulphonic acid catalyses the crosslinking reaction after the DMAE evaporates during the stoving operation. 

Concrete may use plasticizers (e.g., sulphonated melamine and naphthalene formaldehyde condensates), air-entraining agents (aIkyI/aryl sulfonate surfactants), retarders (hydroxy carboxylic acids such as polyethylene glycol mono-p-nonylphenyl ether) and surface washes (benzalkonium chloride) (RAIA 1997). Little has been published on air emissions from concrete additives, their leaching into surface waters appearing to be of greater environmental concern (Ruckstuhl, 2001). 

E/1/0.45 0.45 % condensation polymer of the sulphone melamine with formaldehyde... 

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